1. Field of the Invention
The present invention relates to saws for splitting eviscerated carcasses while the carcass is suspended and continuously moving along a carcass rail. More specifically, the invention relates to automated saws that split the carcass vertically by simultaneously driving the splitting saw vertically to make the cut and horizontally to follow the moving carcass.
2. Description of Related Art
One step in the processing of carcasses, particularly hog carcasses, is to split the carcass after it has been eviscerated. Automated saws for accomplishing this task are known, but they suffer from various problems, including inaccurate cutting and slow speed. Inaccurate cutting is objectionable as it wastes valuable meat and makes subsequent processing more difficult. Slow speed limits the rate at which carcasses can be processed, or requires that multiple splitting machines be installed to process multiple carcasses simultaneously.
U.S. Pat. No. 4,653,150 issued to Leining on Mar. 31, 1987 shows one type of automated carcass splitting saw. The saw shown therein generally consists of a moving U-shaped frame having two vertical legs. The carcass passes between the vertical legs of the frame with the back of the carcass facing one leg and the eviscerated belly on the carcass facing the opposite leg. The U-shaped frame is driven horizontally along a track at a speed that matches the speed of the moving carcass. The back of the carcass is held between a pair of guide plates which extend out from one leg of the frame to position the carcass and a saw is extended out at the top of the opposite leg of the frame to begin cutting and is then driven vertically down to complete the cut.
One problem with this design is that the carcass is not accurately held relative to the saw by the guide plates due to variations in the size and shape of the carcass. This causes the saw to cut to one side or the other of the exact center line of the backbone. This inaccurate cutting relative to the center line of the backbone is objectionable to the meat processing industry.
A second difficulty relates to the weight of the U-frame due to the need to maintain accurate alignment between the opposite vertical legs of the frame while supporting the carcass from the back and driving the saw vertically along the opposite leg of the frame. The lower horizontal elements of the U-frame, needed to connect and rigidly support the two vertical legs of the frame in the correct relationship, tend to be heavy.
Because the entire U-shaped frame must be returned to the starting point as soon as a cut has been completed, excess weight adversely affects the return speed of the saw. This limits the number of carcasses that can be split per hour to speeds below that which are desirable for operating the carcass rail.
An alternative design for a splitting saw is seen in U.S. Pat. No. 5,655,960 issued to Van Horeebeck on Aug. 12, 1997. This machine uses a saw mounted on an arm. The arm is carried on a single vertical leg and is movable vertically along the leg. The leg is part of a frame that moves horizontally along a track to match the speed of the moving carcass. To make the cut, the arm is extended at the top of the frame between the legs of the carcass suspended from the carcass rail.
A back roller is attached to the end of the arm and swings down into contact with the back of the carcass. A front roller is also located on the arm and contacts the interior of the carcass along the backbone as the saw begins its cut. The two rollers hold the carcass in position relative to the saw.
Unfortunately, in this design the saw begins to cut before the rollers achieve good contact with the carcass. This is because the saw and the front roller are mounted on the same extending arm. Extending the saw into contact with the carcass is the only way to extend the front roller into contact with the carcass. Any initial misalignment as the saw begins to cut results in at least a portion of the carcass being cut improperly off the center line of the backbone. Such initial misalignment is difficult to avoid when the cut is started before the rollers have properly aligned the carcass.
A related problem with this design is speed. The arm must be extended between the legs of the carcass before the back roller can be lowered into position to contact the back of the carcass. This extension and positioning of the arm and rollers between the legs of the carcass is time consuming and slows the cutting operation significantly.
There is yet another problem that arises from the mounting of the guide rollers on the same arm carrying the saw. Some processing operations prefer to split the carcass completely, but others prefer to leave a small connecting portion of neck fat and skin at the head of the carcass intact after the backbone has been split so that the two carcass halves remain attached after the splitting operation. In the design described above, it is not possible for the saw to be retracted relative to the carcass (as needed to make a partial cut) without also partially retracting the roller mounted on the same arm. Thus, if it is desired to make a partial cut, the carcass cannot be held accurately in position relative to the saw.
Another speed problem for the above design arises from the necessity of lifting the back roller and supporting arm sufficiently high to pass between the legs of the carcass. Moving any additional distance beyond the minimum needed to position the saw at the top of its cutting point takes additional time and slows processing. The necessity to pass the back rollers between the legs of the carcass also places various other objectionable limitations on the size, shape and rigidity of the arm which limits accurate positioning of the saw relative to the carcass.
Bearing in mind the problems and deficiencies of the prior art, it is therefore an object of the present invention to provide an automated saw where the carcass can be accurately positioned before the saw begins to cut.
It is another object of the present invention to provide an automated saw in which the saw is separately retractable and extendible relative to the guiding mechanism so that the carcass can be partially cut if desired.
A further object of the invention is to provide an automated saw which can operate at higher speeds than prior art designs to accommodate maximum carcass rail speeds.
Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification.